Hitherto, various compounds having anti-ulcer activities have been disclosed in a number of publications. Of these known compounds, 2-(3-carbamoylphenylamino)-N-(3,4-dimethoxyphenethyl)acetamide is disclosed as anti-peptic ulcer agent in Japanese Patent Application (OPI) No. 31027/80 (the term "OPI" as used herein refers to a "published unexamined Japanese Patent Application"). Also, it is disclosed in Japanese Patent Application (OPI) No. 18947/81 that the hydrate of the above compound (hydrated crystals containing three molecules of crystallized water) has stable chemical and physical properties.
However, the above compounds do not necessarily have the sufficient anti-peptic ulcer activities and pharmaceutical properties.